Efficiency of frequency duplexing used for interference elimination

Careful planning of wireless networks is essential to provide reliable communication, especially that microwave links are frequently chosen to interconnect access points within networks. The optimization of such networks belongs to the frequency assignment problems and focuses on setting polarization of the links or allocating the channels in a frequency duplex to reduce or eliminate the interference that might occur between links. In this paper we are aiming to reveal the unexpected difference between these two well-studied problems if the sharpness of the applied beam widths is relaxed. We provide graph theory based analysis and reveal the main differences between frequency duplexing and polarization setting from mathematical point of view. We give numerical bounds for efficiency and show traps of algorithmic solutions working with interference graphs.